The International Brotherhood of Teamsters Airline Division has asked the National Mediation Board to arbitrate its ongoing contract dispute with Denver-based Frontier Airlines.

And, if that doesn’t work, Frontier’s union-represented aircraft technicians, ground service technicians and tool-room attendants could exercise their right to strike — a move that essentially could cripple Frontier’s operations.

“At this point, it is abundantly clear that Frontier is not participating in mediation and indeed has no respect for the process,” Bourne wrote. “The (union) has come to the end of the line in the mediation process and will not suffer further pointless sessions to which the Carrier arrives completely unprepared.”

Frontier said in a statement that it has not seen the letter and that it is ” working in good faith with the Teamsters.”

The latest round of contract negotiations began in February 2012 but stalled,

prompting federal mediators to intervene in August.

The two parties have since met three times with federal mediator Anthony Michael Tosi, with the main points of contention being wages, vacation time and benefits, the union says.

“The union gave a comprehensive economic proposal to the carrier in March 2013,” Bourne wrote. “After repeated requests, the carrier finally responded in June 2014 with a wage proposal of less than 6 percent spread over seven years. The union countered in June 2014 and has yet to receive a response.”

Tosi instructed Frontier to bring an economic proposal to the table for meetings in March, May and June, according to the union, but the airline did not comply.

The mediation board now must decide whether the airline has been bargaining “in bad faith,” said Matthew Fazakas, the contract director for Teamsters Local 455, the Denver unit overseeing the contract.

If both sides then agree to arbitration, a decision will be made. If one doesn’t, the two parties enter a designated “cooling-off period.”

At that point, the union could vote to strike.

“In all honesty, we’re trying to get them to come to the table and negotiate, and they won’t. We were forced into this situation,” Fazakas said. “If they don’t want to negotiate, there are consequences.”

Frontier’s aircraft cleaners also are represented by the union but are under a contract that is not part of this dispute.